Industrial batteries such as those used on fork lift trucks are generally of the flooded lead-acid type which require watering at regular intervals. An increasingly popular means of filling such battery cells with water is with a central watering system (single point watering system) whereby water is supplied through a tube to individual level-control devices in each battery cell. The flow of water to each cell is terminated when the electrolyte in each cell reaches the predetermined level.
A common type of level control device is the float valve as exemplified in U.S. Pat. No. 4,512,378 (Oschmann), U.S. Pat. No. 4,386,141 (Weidner), and U.S. Pat. No. 4,749,633 (Elias). Such float valves rely on the lifting force of a small float to operate the water shut-off valve. While most designs of this type have the float in the acid of the cell, one sub-type has the float in an external chamber as disclosed in U.S. Pat. No. 4,544,004 (Fitter).
The common float valve has fundamental and serious limitations. Due to the necessarily small size of the actuating float, the actuating force is very small, typically about 5 grams. They are therefore susceptible to sticking or jamming by relatively small forces that impede the floats motion, e.g., stickiness, friction, surface tension forces, etc. This leads to a lack of reliability in service.
Another type of level control valve operates on a fluidic operating principle as disclosed in U.S. Pat. No. 4,527,593 (Campau). This type of device uses small rubber-like diaphragms that tend to stick under adverse conditions which can also lead to unreliability.
Another type of valve which overcomes many of the problems of these other type valves operates on a hydrodynamic principle as disclosed in U.S. Pat. No. 4,556,093 (Jones). This type valve relies on the energy of an water stream to provide the shut-off force. Nevertheless, this valve has the limitation that it requires a high-flow water source to enable it to function properly.
Accordingly, one object of the present invention is to provide a means for filling liquid into containers to an accurate and predetermined level that overcomes many of the limitations of the prior art devices.
Another object is to provide a device that will permit both high and low speed filling rates.
A further object is to provide a system that is safer than conventional watering systems.
A still further object is to provide a filling device with low manufacturing costs.
Additional objects, advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those of ordinary skill in the art upon review of the following or may be learned by practice of the invention.